Conventional portable leaf blowers typically comprise a housing having an air inlet and an air outlet, and an elongate blower tube connectable in airflow receiving relation to the air outlet. An electrically powered motor or an internal combustion engine mounted within the housing drives an air impeller, or the like. The air impeller draws a significant amount of airflow into the housing through the air inlet, and blows a forceful airflow out of the housing through the air outlet, and thereafter through the blower tube. The airflow egresses the blower tube through an air egress port to move debris, such as leaves, on a surface being cleaned.
In order to be maximally effective, it is highly desirable to produce the best combination of volume of airflow and speed of airflow. It is generally known in the industry that a certain size of motor or engine along with a certain diameter of blower tube will produce approximately a certain volume and speed of airflow at approximately a known efficiency. On an overall basis, in order to produce an airflow of greater volume and speed, which are generally desirable characteristics, it seems to be a simple matter of using a larger motor or engine. However, since leaf blowers must be carried by individuals, often for a lengthy period of time, it is important to minimize the weight of the leaf blower. It is also highly desirable to minimize the cost of a leaf blower, for marketing and sales purposes. Additionally, more powerful motors and engines are typically noisier for a given design, particularly when internal combustion engines are concerned, such that bigger, more powerful motors and engines are generally less desirable from noise abatement and work-hazard standpoints. It therefore follows that producing the maximum amount of air flow from a motor or engine of low power output is highly desirable, as merely using larger motors or engines to achieve airflow of greater volume and speed is not an entirely acceptable solution.
Accordingly, various prior art devices exist to supposedly produce more effective airflow from leaf blowers, without increasing the size, power, and/or cost of the motor or engine. An example of one such device is disclosed in U.S. Design Pat. No. D382683, issued Aug. 19, 1997, to Henke et al., and entitled Air Nozzle For A Leaf Blower. This air nozzle has an ingress port and three egress ports. The cross-sectional area of the three egress ports is significantly less than the cross-sectional area of the ingress port. Accordingly, the speed of the airflow is greater through the three egress ports than it is through the one ingress port. However, it is believed that the overall cross-sectional area of the airflow produced is smaller than if the nozzle was not present, which may be undesirable. Further, the narrowing of the airflow in this manner typically causes some resistance to airflow, which is also undesirable.
Another type of attachment that has been developed in an attempt to produce more effective airflow in air blowers is a type of Venturi tube that can be used with leaf blowers, and which is described at the following publish link available at the filing date of this application: http://www.thingiverse.com/thing:176094. This attachment device comprises an annular outer wall longitudinally divided by a cone shaped funnel having a reduced diameter central port. A plurality of small oval openings arranged around the circumference of the annular outer wall are adjacent the reduced diameter central port. High speed airflow from the reduced diameter central port draws (entrains) additional air into the interior of the attachment through the small oval openings in an attempt to augment the overall effectiveness of the portable leaf blower that utilizes the attachment. This attachment is less effective in increasing air flow than the present invention, and its design increases the resistance to air flow through the device. Moreover, air flow through a leaf blower fitted with this device is necessarily unidirectional. Also, that air flow through the cone-shaped funnel portion of this device is conducive to clogging and blockage with debris, such as leaves, sticks, stones and rocks, which types of debris is routinely encountered in outdoor use.
It is an object of the present invention to provide a portable leaf blower having improved efficiency.
It is another object of the present invention to provide a high air volume portable leaf blower.
It is another object of the present invention to provide a high air volume portable leaf blower that is efficient in terms of airflow production.
It is another object of the present invention to provide a high air volume portable leaf blower that produces more airflow than a comparable leaf blower having the same power rated motor or engine.
It is still a further object of the present invention to provide a high air volume portable leaf blower having low power consumption.
It is another object of the present invention to provide a high air volume portable leaf blower that is efficient in terms of the amount of airflow produced by an electrically powered motor and impeller.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that is lightweight as compared to portable leaf blowers capable of producing similar air volumes flow rates.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that is not too heavy for a user to use comfortably.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that is not too heavy for a user to use comfortably for an extended period of time.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that can be produced for a competitive cost.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that is relatively quiet for its effective air volume flow rate.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that has minimal resistance to airflow.
It is still a further object of the present invention to provide a high air volume portable leaf blower, wherein the airflow produced by the impeller is not slowed significantly by increased air flow resistance along its path.
It is still a further object of the present invention to provide a high air volume portable leaf blower, wherein the airflow emitted from the blower tube of the portable leaf blower is greater than the airflow originally produced by the impeller.
It is yet a further object of the present invention to provide a high air volume portable leaf blower that is more effective than prior art leaf blowers having comparable weight and/or power ratings.